The object of the proposed experiments is to explore the negative feedback controls that govern the regulation of body weight and food intake in rats and baboons. In particular, the relationship of several peptide hormones, especially insulin, to body weight regulation will be explored with a number of preparations in which either insulin levels or body weight are held constant and the other parameter investigated. Another area of interest is the role of the cerebrospinal fluid and its normal contents in feeding and body weight. Finally, several other hormones, including cholecystokinin and somatostatin, will be investigated regarding their potential role in the system. BIBLIOGRAPHIC REFERENCES: Woods, S.C., and Porte, D., Jr. Insulin and the set-point regulation of body weight. In D. Novin, G.A. Bray, and W. Wyrwichka (Eds,), Hunger: Basic Mechanisms and Clinical Implications, New York: Raven Press, 1976, 237-280. Woods, S.C., and Porte, D., Jr. Neural pancreatic interactions: A conference. Federation Proceedings, 1976, 35, 1117-1121.